His one unique beam card is the Crasher Ball (beam, 19cc, 25pow) which does a good amount of damage and is worth putting on your limits. You may also want to consider putting Cont Punch or Cont Kick on your limit slot as well, in case you need to utilise some non-beam attacks.

Yes, there are the Purple Comet (beam, 28cc, 40pow) and P Comet Z(melee, 31cc, 50pow) cards that he can use in combination with Burter, but team battles are rare and those cards are so insanely powerful anyway that it’s not worth upgrading Jeice’s Str stat for (at least, not just for that purpose).